This method even worked for Wiresharking all PS3 traffic in real time for a GTA Online session, running the tcpdump on a little plastic old mipsel SoC OpenWrt router that was also doing all the routing (not a passive sniffing box), without noticeable effect on gameplay. (I was trying to detect cheaters.)

BTW, for anyone new to tcpdump, you can also specify selectors/filtering on the command line, to reduce the traffic. The filtering in Wireshark is on top of that.